Environmental Performance of Marble Tile Life Cycle

J. Environ. Res. 34(1) (2012): 51-63 ENVIRONMENTAL PERFORMANCE OF MARBLE TILE LIFE CYCLE การประเมินผลกระทบต่อสิ่งแวดล้ อมตลอดวัฏจักรชีวิตของกระเบื ้องหินอ่อน Nachawit Tikul1 Faculty of Architecture and Environmental Design, Maejo University, Chiang Mai 50290, Thailand ณัชวิชญ์ ติกลุ 1 1 คณะสถาปั ตยกรรมศาสตร์ และการออกแบบสิ่งแวดล้ อม มหาวิทยาลัยแม่โจ้ จ.เชียงใหม่ 50290 ประเทศไทย received : October 13, 2011 accepted : January 26, 2012 Abstract Accurate data and information about life cycle environmental impacts of building materials are critical for environmental-friendly building design. This paper reports the findings of environmental impacts assessment of marble tiles produced in Thailand. The life cycle assessment (LCA) approach was employed and the ecoindicator 95 methodology was used in the assessment. Six impact categories were assessed; global warming, acidification, ozone depletion, eutrophication, winter smog, and summer smog. The results show that manufacturing phase contributes the highest impacts compared with other phases of the marble tile life cycle, and the block cutting process is the greatest contributor. Transportation of finished products to building sites also contributes significantly to environmental impacts. Among the six impact categories assessed, acidification is the highest relative value followed by global warming and winter smog. It is suggested that to minimize environmental impacts of the life cycle of marble tiles, the production of marble should be improved and emphasis should be given on reduction of energy usage in block cutting. In addition, tiles from the sources nearest to building sites should be selected for reducing environmental impact values from transportation of finished products phase. Keywords: life cycle assessment, marble tile, environmental impact, building material บทคัดย่ อ รายละเอียดที่เกี่ยวกับผลกระทบต่อสิ่งแวดล้ อมของวัสดุก่อสร้ างที่มีความสําคัญสําหรับการออกแบบอาคารเป็ น มิตรกับสิ่งแวดล้ อม บทความนี ้ได้ แสดงผลการประเมินผลกระทบด้ านสิ่งแวดล้ อมของกระเบื ้องหินอ่อนที่ผลิตในประเทศไทย การประเมินผลกระทบต่อสิ่งแวดล้ อมของกระเบื ้องหินอ่อนนีใ้ ช้ วิธี ecoindicator 95 ในการประเมินตลอดวัฏจักรชีวิตของ  corresponding author E-mail : [email protected] Phone : +66-8132-57872 ; Fax :+66-5387-33367 51 J. Environ. Res. 34(1) (2012): 51-63 กระเบื ้องหินอ่อนซึ่งแบ่งเป็ น 8 ช่วงชีวิต ได้ แก่ การทําเหมือง การขนส่งวัตถุดิบ การผลิตหินอ่อน การขนส่งกระเบื ้องหินอ่อน การติดตัง้ การใช้ งานและการทําลาย การขนส่งเศษกระเบื ้อง และการฝั งกลบ โดยวิเคราะห์คา่ ผลกระทบต่อปั ญหาภาวะโลก ร้ อน ภาวะฝนกรด การลดลงของโอโซน การมีสารอาหารของพิชในนํ ้าเกินสมดุล และปั ญหาหมอกควันในบรรยากาศ ผลการ ประเมินพบว่ากระบวนการผลิตหินอ่อนส่งผลกระทบสูงสุดเมื่อเทียบกับช่วงชีวิตอื่น ๆ ของกระเบื ้องหินอ่อนโดยเฉพาะอย่าง ยิ่งขันตอนการตั ้ ดก้ อนหินอ่อน ช่วงการขนส่งกระเบื ้องหินอ่อนไปยังสถานที่ก่อสร้ างถือเป็ นประเด็นสําคัญอีกประเด็นหนึ่งที่ ส่งผลกระทบต่อสิ่งแวดล้ อมในปริ มาณมาก นอกจากนีย้ งั พบว่าผลกระทบที่เกิดขึ ้นส่งผลต่อปั ญหาภาวะฝนกรดมากที่สดุ รองลงมาเป็ นปั ญหาภาวะโลกร้ อนและปั ญหาการเกิดหมอกควันในฤดูหนาว ดังนันเพื ้ ่อลดผลกระทบด้ านสิ่งแวดล้ อมจากวัฏ ดก้ อนหินอ่อน จักรชีวิตของกระเบื ้องหินอ่อน ผู้ผลิตควรปรับปรุ งกระบวนการผลิตโดยการลดการใช้ พลังงานในขันตอนการตั ้ นอกจากนีผ้ ้ อู อกแบบหรื อเจ้ าของอาคารควรเลือกใช้ กระเบื ้องหินอ่อนจากแหล่งที่ใกล้ สถานที่ก่อสร้ างมากที่สดุ เพื่อลดค่า ผลกระทบต่อสิง่ แวดล้ อมจากการขนส่งกระเบื ้องหินอ่อน คําสําคัญ: การประเมินวัฏจักรชีวิตผลิตภัณฑ์, กระเบื ้องหินอ่อน, ผลกระทบต่อสิ่งแวดล้ อม, วัสดุก่อสร้ าง Introduction Buildings contribute a great deal to environmental impacts both in terms of energy consumption and depletion of natural resources (1). The impacts are generated both in the construction phase and the use phase. Efforts have been made to reduce environmental impacts of buildings by various parties in various ways such as improving construction methods, developing more appropriate methodologies and techniques for assessing environmental impacts of buildings, and selecting environmental–friendly materials. In order to assess the environmental impacts of buildings accurately, the life cycle approach has to be employed (1, 2). Assessing the impacts of only part of the life cycle of buildings could result in misleading information about the impacts. If, for example, one selects materials that result in the reduction of energy consumption in the use phase but the production of such materials generates high impacts, one might end up generating higher impacts overall. As materials are essential components of buildings, knowledge of accurate values of environmental impacts of building materials is of critical importance for accurate assessment of overall environmental impacts of buildings. Life cycle assessments (LCA) of various building materials including concrete , linoleum, vinyl, carpet, wood, brick, particleboard and so on have been performed by many investigators (3-10). The types of materials that have been assessed are still limited, however, and there are numerous building materials that need to be investigated. Furthermore, the impact values in the literature for the same materials vary widely from one study to another. There are many factors that influence environmental impact values of building materials including plant locations and manufacturing technologies employed. There is a need therefore to assess environmental impacts of materials produced in various locations of the world in order to acquire 52 J. Environ. Res. 34(1) (2012): 51-63 accurate environmental impact values of specific building materials so that impact assessment of building can be accurately made. Marble has been used as a building material for a long time and is quite popular among practicing architects in many countries including Thailand. Environmental impact assessment of marbles in Italy have been investigated by Nicoletti et al. (11) who found that the most important impact categories of the life cycle of marble tiles were global warming, human toxicity and acidification and Traverso et al. (12) who found that the embodied energy values of Sicilian marble tiles was 1,772 MJ/m3. Environmental impact assessment of marble tile has never been conducted in Thailand where a substantial tonnage of marbles is produced and consumed annually. The objective of this research is to assess environmental impacts of marble tiles produced by a firm in Saraburi Province about 100 kms north of Bangkok, the largest marble tile producer in Thailand. Marble tile life cycle of the study The life cycle of marble tiles can be divided into 8 phases as shown in Figure 1. The first phase is mining which involves drilling holes in the x-,y-, and z- directions. Diamond saws are then placed in the holes for cutting the marble into large blocks. Flowing water was used as lubricant during cutting. The marble blocks are then ‘pushed’ out (pushing) using a jack hammer and a hydraulic ram before being split into smaller blocks (splitting) by a diamond saw. The second phase, hauling, involves moving the marble blocks from the mine to manufacturing plants. In the case being investigated, the marble blocks are loaded in large trucks using hydraulic crane. The transportation distance between the mine and the plants is approximately 1 km. The third phase is the marble tile production. Marble blocks are cut into sheets of required thickness and further cut into required sizes using gang saw. The tiles are then polished to specifications before being sorted colours of the tile and placed on pallets ready for transportation to customers or building sites which is the fourth phase of the life cycle. The next four phases of marble tiles are; construction or installation, use phase, demolition, and end-of-life phases. The installation phase involves placing the tiles according to the required pattern using cement as binder. The use phase involves cleaning the tiles with tap water once a week throughout their useful life (about 40 years). The demolition and end-of-life phases include actual demolition and transportation of wastes to landfill sites where the marble tile wastes are finally buried. 53 J. Environ. Res. 34(1) (2012): 51-63 Extraction of Raw Materials Raw Material Transportation Production of Marble Tiles Transportation of Finished Products Construction Use Transportation of Wastes End of Life Marble Tiles Life Cycle Figure 1 The life cycle phases of marble tiles Methodology The data were measured, collected and assessed using the LCA methodology in accordance with ISO 14040:2006 (13) and ISO14044:2006 (14). The inventory data of the system were characterized, normalized and weighted according to the Ecoindicator 95 methodology (15). Goal and scope The goal of this study was to assess the LCA impact of marble tiles. The impacts corresponding to various life cycle phases were determined and those with high values noted. The impact values will be useful both for the assessment of marble tiles as a building material and for improving the impact values for this particular plant through appropriate measures such as modifications of manufacturing process. The study was conducted in a marble tile firm in Saraburi Province, Thailand. All the life cycle phases, from cradle-to-grave, of marble tiles are included in the study. The functional unit used in this study is 1 ton of 30x60x1.9 cm3 tiles (51.3 kg/m2). 54 J. Environ. Res. 34(1) (2012): 51-63 Assumption All the machines and equipment as well as consumables used in the life cycle of marble tiles such as diamond saws and lubricants are not included in this study. Water used in the process is fully recycled but the water recycle process is excluded in this calculation. Moisture during the manufacturing process is in the air and is not considered because it is in a very small amount. The crushing of marble wastes from the production and the demolition of installed marble tiles are also excluded from the study. It is assumed that there are no chemicals in the process of installation and use phase. In the end-of-life phase, all of marble fragments are taken to the landfill. Inventory analysis Detailed inventory data of energy and materials consumption and the pollutions generated in the life cycle of 1 ton marble tiles are shown in Figure 2. 55 J. Environ. Res. 34(1) (2012): 51-63 Materials from Quarries 43.83 T Electricity 105.79 kWh Ground Water 405.53 L Motor Oil 0.23 L Diesel 0.67 L Hydraulic 0.28 L Electricity 139.83 kWh Reuse Water 559.29 L Hydraulic 0.23 L Electricity 96.37 kWh Ground Water 282.48 L Diesel 1.69 L Wax 0.43 kg Electricity 17.15 kWh Reuse Water 188.32 L Hydraulic 0.11 L Motor Oil 0.46 L Diesel 30 L Hydraulic 0.29 L Life Cycle Assessment of Cement 0.487 T Tap Water 146.19 L Tap Water 20272.9 L Mining Marble Blocks 1.68 T Transportation 1 Marble Blocks at the Plant 1.68 T Block Cutting Raw Marble Tiles 1.177 T Polishing Particular 7.6x10-6 T Waste Water 405.53 L Solid Waste 42.149 T Moisture Waste Water 559.28 L Solid Waste 0.497 T Waste Water 282.26 L Moisture Moisture 30x60 Marble Tiles 1.00 T Transportation 2 Waste Water 559.28 L Solid Waste 0.171 T Particular 9.5x10-6 T 30x60 Marble Tiles at Construction Site 1.00 T Construction Particular 7.6x10-7 T Marble Floor 1.48 T Using (40 Years) Waste Water 20272.9 L Useless Marble Floor 1.48 T Diesel 8.88 L Transportation Solid Waste at the Calcium Plant 42.149 T Particular 2.8x10-6 T Marble Tiles 1.176 T Cutting Transportation Particular 6.68x10-6 T Useless Marble Floor at Site 1.48 T Landfill Figure 2 Inventory data for 1 Mg marble tile production 56 Moisture Filter Water for Reusing Sludge J. Environ. Res. 34(1) (2012): 51-63 It can be seen in Table 1 that the manufacturing phase (block cutting, polishing and cutting) consumes the greatest amount of energy (2330 MJ) or 53% of energy consumed throughout the life cycle of the marble tiles. The block cutting is the unit process that consumes a large amount of energy (1286 MJ). Transportation of finish products to building sites (assuming the transportation distance of 30 km) consumes 1092 MJ of energy, the second largest amount. Energy consumption values of other life cycle phases are shown in Table 1. Table 1 Energy consumption (per 1 Mg marble tile) Electric Energy Diesel Life Cycle Phase (kWh) (L) Mining 105.79 NC Transportation I NC 0.67 Manufacturing Block Cutting 139.83 NC Polishing 96.37 NC NC Cutting 17.15 30 Transportation II NC Construction NC NC Using NC NC Transportation III NC 8.88 Landfill NC 0.29 Total 612.49 39.84 Source: Information from the business operator 1 kWh = 9.2 MJ Diesel = 36.42 MJ/L NC = No consumption Total (MJ) 973.3 24.4 13.74 0.34 1286.4 886.6 157.8 1092.6 NC NC 323.4 10.6 7085.9 18.15 12.51 2.23 15.42 0.00 0.00 4.56 0.15 100 % 52.89 Impact assessment Ecoindicator 95 was used to assess the environmental impacts of the marble tiles. Six impact categories were considered; global warming, eutrophication, ozone depletion, acidification, summer smog, and winter smog. The impact values are shown in Table 2. 57 J. Environ. Res. 34(1) (2012): 51-63 Table 2 Environmental impact values of 1 Mg marble tile Impact category Unit Amount Greenhouse kg CO2 3.68E+02 Ozone layer kg CFC11 1.57E-04 Acidification kg SO2 1.50E+00 Eutrophication kg PO4 1.60E-01 1.81E-01 Summer smog kg C2H4 Winter smog kg SPM 7.87E-01 Detailed examination of the impact values of various life cycle phases reveals that the manufacturing phase yields the greatest impact in 3 categories; global warming, acidification, and winter smog. Transportation of finished products to building sites yield the highest impact values in ozone depletion, eutrophication, and summer smog categories. Comparisons of the impact values of various life cycle phases in various impact categories are shown in Figure 3. 58 J. Environ. Res. 34(1) (2012): 51-63 kgCO2eq 1.20E+02 kgCFC11eq 7.50E-05 1.00E+02 8.00E+01 6.00E-05 4.50E-05 6.00E+01 3.00E-05 4.00E+01 2.00E+01 1.50E-05 Disposal Transportation3 Using Disposal Transportation3 Using Construction Manufacturing Acidification Transportation2 Transportation1 Life cycle phase kgPO4eq 4.50E-02 3.75E-02 3.00E-02 2.25E-02 1.50E-02 7.50E-03 0.00E+00 Extraction Disposal Using Transportation3 Construction Transportation2 Manufacturing Transportation1 Life cycle phase Ozone Layer kgSO2eq 5.40E-01 4.50E-01 3.60E-01 2.70E-01 1.80E-01 9.00E-02 0.00E+00 Extraction Construction Manufacturing Global Warming Transportation2 0.00E+00 Transportation1 Life cycle phase Extraction Disposal Using Transportation3 Construction Transportation2 Manufacturing Transportation1 Extraction 0.00E+00 Life cycle phase Eutrophication kgC2H4eq 7.20E-02 kgSPM eq 4.20E-01 3.50E-01 6.00E-02 4.80E-02 2.80E-01 2.10E-01 1.40E-01 Disposal Transportation3 Using Construction 7.00E-02 0.00E+00 Manufacturing Life cycle phase Transportation2 Disposal Using Transportation3 Construction Transportation2 Manufacturing Transportation1 Extraction 0.00E+00 Transportation1 2.40E-02 1.20E-02 Extraction 3.60E-02 Life cycle phase Winter Smog Summer Smog Figure 3 Comparisons of the impact values of various life cycle phases in the six categories being studied Impact values of various processes in the manufacturing phase are shown in Table 3. It can be seen that block cutting contributes the greatest environmental impact due to high energy consumption by the process. Ozone depletion category is affected the most by polishing process due to large energy requirement in moving the tiles to polishing stations. 59 J. Environ. Res. 34(1) (2012): 51-63 Table 3 Impact values in the marble tile production Impact category Unit Block Cutting Greenhouse kg CO2 57.36 Ozone layer kg CFC11 2.41E-06 0.25 Acidification kg SO2 0.015 Eutrophication kg PO4 0.0047 Summer smog kg C2H4 Winter smog kg SPM 0.19 Winter smog 16% Polishing 40.22 2.54E-06 0.18 0.011 0.0041 0.14 Cutting 8.28 3.47E-07 0.036 0.002 6.79E-04 0.028 Greenhouse 23% Summer smog 7% Ozone layer 5% Eutrophication 6% Acidification 43% Figure 4 Percentage of various impact categories Among the six impact categories assessed, acidification is the highest followed by global warming and winter smog. Relative values for other categories are shown in Figure 4. The normalization and weighting factors used in the calculation are shown in Table 4 (15). The main reason for such results is the large energy consumption in the manufacturing phase. 60 J. Environ. Res. 34(1) (2012): 51-63 Table 4 Normalization and weighting factors Impact category Normalization factor Greenhouse 0.0000765 Ozone layer 1.08 Acidification 0.00888 Eutrophication 0.0262 Summer smog 0.0558 Winter smog 0.0106 Weighting factor 2.5 100 10 5 2.5 5 Discussion The environmental impact values of marble tiles from this research can be used in impact assessment of buildings as well as for comparing with the values of other floor covering materials such as ceramic tiles. It would be beneficial to building designers who are keen to include environmental impacts consideration in their designs. The values can also be used for comparing environmental impacts of marble tiles from different sources. In comparing and using the impact values, however, one should be careful to compare the ‘comparable’ values and employ the full life cycle value for comparison where possible. The phase-by-phase presentation of impact data in this research would facilitate the use of the data for both comparison and impact assessment purposes. The finding from this research that manufacturing phase contributes the highest impact values agrees with the findings of other investigators (11, 12) although the actual values are different. The impacts resulting from transportation of finished products to building sites or customers, hardly considered in other work, were also found to be quite significant in relation to the overall value in the present study. This means that in order to minimize the impacts of life cycle of marble tiles, manufacturers should reduce the energy consumed in their production processes, especially the block cutting, because this unit process takes a long time to cut each piece of marble block from the quarry (11). Therefore, the technology for cutting marble blocks should be improved to reduce the energy consumption. In addition, designers or consumers should select locally produced marble tiles, which is very easy to do. LCA is a complex process requiring numerous related data. In conducting the assessment of marble tiles in this project, several necessary data have not been specifically determined in Thailand, and the values of such data in the literature were employed. This is the key limitation of this research. 61 J. Environ. Res. 34(1) (2012): 51-63 Conclusions The ecoindicator 95 methodology was used in the life cycle impact assessment of 1 T of marble tiles. LCA of environmental impacts of marble tiles yields the following values; global warming 368 kgCO2, ozone layer 1.57E-04 kgCFC11, acidification 1.50 kgSO2, eutrophication 0.16 kgPO4, summer smog 0.18 kgC2H4 and winter smog 0.78 kgSPM. The manufacturing phase results in the highest impact values due to large energy consumption and the block cutting process is the greatest contributor. Transportation of finished products to building sites or customers also contributes significantly to environmental impacts. Acidification category is the highest among the six impact categories assessed followed by global warming and winter smog. It is suggested that to minimize environmental impacts of the life cycle of marble tiles, the energy consumed in the production processes, especially the block cutting, should be reduced. In addition, designers or consumers should select locally produced tiles to minimized environmental impact values from transportation of finished products phase. 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